ANALYSIS FOR BEST AVAILABLE RETROFIT TECHNOLOGY – 

EXEMPTION ANALYSIS 

GEORGIA-PACIFIC CEDAR SPRINGS LLC 

August 1, 2008 (Revised) 
Cedar Springs Mill BART Exemption Report 

August 1, 2008 (Revised) 

BART Exemption CSO Model Report (80108).doc ii

1.0 INTRODUCTION............................................................................................................. 3 

1.1. Overview of the Regional Haze BART Process............................................................... 3 

1.2. Organization of the Report ............................................................................................... 5 

2.0 SITE DESCRIPTION AND EMISSION INVENTORY .............................................. 6 

3.0 VISTAS CONTRIBUTION TO CALPUFF MODELING ......................................... 13 

4.0 MODEL DISCUSSION.................................................................................................. 14 

4.1 General Procedures .................................................................................................... 14

4.2 CALPUFF Configuration........................................................................................... 14 

5.0 RESULTS AND DETERMINATION OF IMPAIRMENT........................................ 20 

5.1 Impact Threshold........................................................................................................ 20 

5.2 Presentation of Modeling Results.............................................................................. 20 
Cedar Springs Mill BART Exemption Report 

August 1, 2008 (Revised) 

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1.0 INTRODUCTION 

1.1. Overview of the Regional Haze BART Process 

Under regional haze regulations, the Environmental Protection Agency (EPA) has issued 

final guidelines dated July 6, 2005 for Best Available Retrofit Technology (BART) 

determinations (70 FR 39104-39172). The regional haze rule includes a requirement for 

BART for certain large stationary sources, such as Georgia-Pacific Cedar Springs LLC’s 

(GP) pulp & paper facility in Cedar Springs, Georgia. Sources are BART-eligible if they 

meet three criteria concerning (1) potential emissions of visibility-impairing pollutants, 

(2) the date when the source was put in operation, and (3) whether they fall within one of 

the source categories listed in the guidance. The guidance requires a BART engineering 

evaluation using five statutory factors for any BART-eligible source that can be 

reasonably expected to cause or contribute to impairment of visibility in any Class I areas 

protected under the regional haze rule. (Note that, depending on the five factors, the 

evaluation may result in no control.) Air quality modeling is an important tool available 

to the States to determine whether a source can be reasonably expected to contribute to 

visibility impairment in a Class I area. 

The process of making a BART determination consists of four steps: 

1) Identify whether a source is “BART-eligible” based on its source category, when 

it was put in service, and the magnitude of its emissions of one or more “visibilityimpairing” air pollutants. The BART guidelines list 26 categories of stationary 

sources that are BART-eligible. Sources must have been put in service between 

August 7, 1962 and August 7, 1977. Finally, a source is eligible for BART if 

potential emissions of visibility-impairing air pollutants are greater than 250 tons 

per year. Qualifying pollutants include primary particulate matter (PM10) and 

gaseous precursors to secondary fine particulate matter, such as SO2 and NOx. 

Georgia Environmental Protection Division (EPD) has determined that neither 

ammonia nor volatile organic compounds (VOCs) should be included as visibilityimpairing pollutants for BART eligibility. 
Cedar Springs Mill BART Exemption Report 

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2) Determine whether a BART-eligible source can be excluded from BART 

controls by demonstrating that the source cannot be reasonably expected to cause or 

contribute to visibility impairment in a Class I area. The preferred approach is an 

assessment with an air quality model such as CALPUFF or other appropriate model 

followed by comparison of the estimated 24-hour visibility impacts against a 

threshold above estimated natural conditions to be determined by the States. The 

threshold to determine whether a single source “causes” visibility impairment is set 

at 1.0 deciview (dv) change from natural conditions over a 24-hour averaging 

period in the final BART rule (70 FR 39118). The guidance also states that the 

proposed threshold at which a source may “contribute” to visibility impairment 

should not be higher than 0.5 dv although, depending on factors affecting a specific 

Class I area, it may be set lower than 0.5 dv. The test against the threshold is 

“driven” by the contribution level, since if a source “causes”, by definition it 

“contributes”. 

3) Determine BART controls for the source by considering various control options 

and selecting the “best” alternative, taking into consideration: 

a) Any pollution control equipment in use at the source (which 

affects the availability of options and their impacts), 

b) The costs of compliance with control options, 

c) The remaining useful life of the facility, 

d) The energy and non air-quality environmental impacts of 

compliance, and 

e) The degree of improvement in visibility that may reasonably be 

anticipated to result from the use of such technology. 

If a source agrees to apply the most stringent controls available to BART-eligible 

units, the BART analysis is essentially complete and no further analysis is 

necessary (70 FR 39165). 
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4) Incorporate the BART determination into the State Implementation Plan for 

Regional Haze. 

Step 2 described above reflects 40 CFR Part 51 Appendix Y which states that an eligible 

source “can use dispersion modeling to determine that an individual source cannot 

reasonably be anticipated to cause or contribute to visibility impairment in a Class I area 

and thus is not subject to BART.” (70 FR 39162) This “individual source attribution 

approach” determines if a BART-eligible source (i.e., collection of eligible emission units 

at a source) is predicted to cause or contribute to visibility impairment in a Class I area. 

As mentioned above, a predicted impact of 1.0 dv change or more is considered to 

“cause” visibility impairment, and a predicted impact of 0.5 dv change or more is 

considered to “contribute”. Any source determined to cause or contribute to visibility 

impairment in any Class I area is subject to BART and will also complete additional 

visibility impact analyses. 

1.2. Organization of the Report 

Section 2 presents facility-specific information. Section 3 presents the contribution by 

VISTAS for the BART analyses. Section 4 summarizes the modeling approach, and model 

configuration. Section 5 presents the criteria and processing of model results to 

demonstrate what impairment, if any, the facility is predicted to create in the Class I areas. 

The CALPUFF model input and output files are provided on electronic media enclosed 

with this report, a file index for which is presented in the appendix. 
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2.0 SITE DESCRIPTION AND EMISSION INVENTORY 

GP operates the Cedar Springs Mill in Early County. The facility is located in the 

southwestern portion of Georgia, approximately two miles west of the intersection of 

Highways 370 and 273, along the east bank of the Chattahoochee River. The facility 

manufactures unbleached linerboard and corrugating medium with virgin pulp using both 

the Kraft and neutral sulfite semi-chemical (NSSC) processes. Additional pulp is 

produced from recycled fiber sources, specifically old corrugated containers (OCC) and 

double-lined Kraft clippings (DLK). The facility is located in a rural area, with almost no 

residential areas are near the Mill. Figure 1 depicts the location of the Mill and illustrates 

the adjacent terrain. Table 1 presents the BART-eligible emission unit inventory for the 

BART exemption analysis. 

Table 1. Model Parameters for BART-Eligible Sources at GP Cedar Springs 

 LLC (km) ref: VISTAS

Permit 

ID Source Description 

Stack 

Ht 

(ft) East North 

Elevation 

(ft) 

Stack 

Diameter 

(ft) 

Exit 

Velocity 

(ft/sec) 

Exit 

Temp 

(deg F) 

R402N Recovery Boiler No. 3 247 1133.484 -905.071 117.1 9 44.7 413 

R402S Recovery Boiler No. 3 247 1133.483 -905.075 117.1 9 44.7 413 

R406 Smelt Dissolving Tank No. 3 247 1133.500 -905.074 117.1 6 23.1 157 

U500 Power Boiler No. 1 350 1133.491 -905.178 117.1 14.5 34.1 140 

U501 Power Boiler No. 2 350 1133.501 -905.179 117.1 14.5 34.1 128 

L600 Lime Kiln No. 1 82 1133.574 -904.843 117.1 6 31.7 170 

L601 Lime Kiln No. 2 90 1133.558 -904.835 117.1 6 31.7 170 

Table 2 presents the worst-case 24-hour average emissions for worst case 24-hr actual for 

existing sources submitted to EPD in July 2007. Emission rates for the smelt dissolving 

tank and recovery boiler reflect actual operating history during the baseline years 

evaluated by the Mill. Other sources have been modified since the baseline period as 

follows: 

• Power Boiler 1 and 2 completed modifications in 2007 and 2008 for an overfire 

air system (by Mobotec), new Foster&Wheeler Low-NOx burners and wet 
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August 1, 2008 (Revised) 

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scrubber improvements under existing permits. The Mill installed Continuous 

Emission Monitors (CEM) for sulfur dioxide and nitrogen oxides on Power Boiler 

1 and 2 over the past 24 months. 

• Lime Kiln 1 and 2 completed modifications with a lime mud dryer in June 2007. 

The mill installed a new wet scrubber on Lime Kiln 2 and accepted lower PM10

emission rates for both kilns. 

680500 681500 682500 683500 684500 685500 686500

UTM NAD83 E (m) Zone 16

Figure 1, Topographic Map of Cedar Springs and Vicinity

3446000

3447000

3448000

3449000

3450000

3451000

3452000

UTM NAD83 N (m) Zone 16

The Mill has operated a CEM on Recovery Boiler No. 3 for sulfur dioxide periodically 

since November 2004 and nitrogen oxides for approximately 30 days in December 2006. 

Short-term emissions of SO2 ranged from near zero to above 250 parts per million (ppm). 

For periods when black liquor is fired continuously at capacity, the average daily 

emission rates are lower. 
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Table 2. Base Case Emissions Inventory of Cedar Springs Mill BART Sources, 

Prepared July 2007 

 

24-hour Average Emission Rate (lb/hr) 

Emission Unit SO2 NOx PM / PM10

Lime Kiln Nos. 1 and 2 30 30.93 29.8 

Recovery Furnace No. 3 120 85 52.2 

Smelt Dissolving Tank 14.1 2.6 15.2 

Power Boiler No. 1 1377 262 63 

Power Boiler No. 2 1377 262 63

Total 2918 642.5 223.2 

 

Since early 2007, the Mill has been developing construction plans and an air permit 

application for the evaporator and recovery areas. The list of modified equipment 

includes the evaporation stage prior to the recovery boiler. In considering recovery boiler 

physical modifications, the Mill reviewed the BACT limits for its other two existing 

recovery boilers. The current air permit limits SO2 emissions for Recovery Boiler Nos. 1 

and 2 to 300 ppm. In addition, the Mill has continued to operate a SO2 CEM for 

Recovery Boiler No. 3. The additional CEM data shows that the maximum daily 

emissions in the current operations can exceed 200 ppm. However, the mill expects that 

after the proposed evaporator are repairs are completed, that the boiler will be 

consistently run with higher solids content and thus more controllable for SO2 emissions. 

After discussions with EPD in September 2007, the Mill reviewed the hourly CEM data 

and the CALPUFF analyses. The Mill has determined that two operating scenarios are 

feasible following modifications to the evaporator, recovery and power boiler areas. 

These scenarios represent the range of SO2 emission rates from the Recovery Boiler 

No. 3 and Power Boilers Nos. 1 and 2 that are being evaluated to demonstrate that the 

BART-eligible source at CSO does not cause or contribute to visibility impairment. 

Scenario 1 - Improve evaporation and add caustic to existing wet scrubbers: 

Limit daily average Recovery Boiler No. 3 SO2 emissions to 350 ppm when 
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liquor is in the boiler. 

Limit daily average Power Boiler Nos. 1 and 2 SO2 emissions to 135 lbs/hr each. 

Scenario 2 – Improve combustion on Recovery Boiler No. 3 and add caustic to 

existing wet scrubbers: 

Limit daily average Recovery Boiler No. 3 SO2 emissions to 90 ppm when liquor 

is in the boiler 

Limit daily average Power Boiler Nos. 1 and 2 SO2 emissions to 350 lbs/hr each. 

Table 3 summarizes the emission rates for the two scenarios. 

Table 3. Alternate Operating Scenarios: Emissions Inventory of Cedar Springs Mill 

 SO2

Model ID (lbs / hr) 

Scenario 1: 

Power Boiler No. 1 U500 135 

Power Boiler No. 2 U501 135 

Recovery Boiler No. 3 – North Stack R402N 411 

Recovery Boiler No. 3 – South Stack R402S 411

Subtotal 1,091 

 

Scenario 2: 

Power Boiler No. 1 U500 350 

Power Boiler No. 2 U501 350 

Recovery Boiler No. 3 – North Stack R402N 106 

Recovery Boiler No. 3 – South Stack R402S 106

Subtotal 911 

 

Optional equipment modifications for Scenario 1 include repaired concentrator sets, a 

new caustic day tank and control system with CEM for Power Boilers Nos. 1 and 2, and a 

new lift station to connect power boiler scrubber blowdown to the waste water treatment 

system. 

Optional equipment modifications for Scenario 2 include new concentrator sets 

(potentially new evaporators and a crystallizer), a new multi-level air system for 

Recovery Boiler No. 3, a new caustic day tank and control system with CEM for Power 
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Boilers Nos. 1 and 2, and a new lift station to connect power boiler scrubber blowdown to 

the waste water treatment system. For normal operating times when liquor is in the 

boiler, Recovery Boiler No. 3 typically achieves the emission rates under Scenario 2 

using the existing equipment. 

Tables 4 and 5 summarize the emission rates modeled in the two BART exemption 

scenarios on a tons per year and pound per hour basis, respectively. SO2 emissions 

represent potential emissions after the previously described modifications to the 

Recovery Boiler No. 3 and Power Boilers Nos. 1 and 2. SO4 emissions are estimated as a 

percentage of the SO2 mass emission rate based no the characteristics of fuel combusted 

in each emission unit. NOX and PM10 emissions represent allowable emissions 

established by enforceable Emission Caps, Federal Rule Standards, and SIP Rule 

Standards in the current Title V Operating Permit No. 2631-099-0001-V-02-0 

(February 21, 2007) and V-02-2 (April 18, 2007). Allowable emissions were modeled 

instead of actual emissions to confirm that these operating scenarios do not cause or 

contribute to visibility impairment and are therefore exempt from BART. 

Table 4. Summary of BART Exemption Scenarios 

Emission Rate (tpy) 

Scenario SO2 SO4 NOX PM10

Base Case 12,781 569 2,814 978 

Alternative Scenario 1 5,104 164 2,824 1,238 

Alternative Scenario 2 4,136 166 2,824 1,238 
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Table 5. Summary of Modeled BART Exemption Alternative Scenarios 

24-hour Average Emission Rate (lb/hr) 

Source SO2 SO4* NOX PM10

Smelt Dissolving Tank No. 3 47.0 0 2.6 45.0 

Lime Kiln No. 1 13.54 0.32 14.06 29.8† 

Lime Kiln No. 2 16.25 0.36 16.87 29.8† 

Subtotal 76.8 0.68 33.53 104.6 

 

Scenario 1 

Recovery Boiler No. 3 – North 410.6 12.46 45 26.0 

Recovery Boiler No. 3 – South 410.6 12.46 45 26.0 

Power Boiler No. 1 135.0 5.94 262 63.0 

Power Boiler No. 2 135.0 5.94 262 63.0 

 

Scenario 2 

Recovery Boiler No. 3 – North 105.6 3.20 45 26.0 

Recovery Boiler No. 3 – South 105.6 3.20 45 26.0 

Power Boiler No. 1 350.0 15.4 262 63.0 

Power Boiler No. 2 350.0 15.4 262 63.0 

 

Total Scenario 1 1167.9 37.5 647.5 282.6 

Total Scenario 2 987.9 37.9 647.5 282.6 

* SO4 emissions are estimated as a fixed percentage of the SO2 mass emission rate based on the 

characteristics of fuels combusted. The SO4/SO2 fractions utilized are approximately 2.3% for 

lime kilns, 3.0% for recovery boilers, and 4.4% for power boilers. 

† PM10 emissions from each lime kiln were conservatively modeled as the total allowable 

emission rate from both lime kilns (i.e., 17.62 lb/hr for Lime Kiln No.1 and 12.28 lb/hr for 

Lime Kiln No. 2). 

The analysis applied PM10 speciation profiles provided by National Council for Air & 

Stream Improvement1 and the National Park Service2 to determine emission rates for all 

other visibility affecting pollutants modeled in CALPUFF. Table 6 presents speciated 

emission rates for each emission unit. Note that the speciation profile was applied using 

the POSTUTIL module to the total PM10 emission rate that was modeled in CALPUFF. 

 

1 NCASI guidance document. 

2 National Park Service PM10 Speciation Profile for Utility Oil Boiler with Scrubber, 

http://www.nature.nps.gov/air/permits/ect/ectOilFiredBoiler.cfm 
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Table 6. Characteristic PM10 Speciation Profiles

Source PMC PMF EC SOA 

Smelt Dissolving Tank 10.8% 81.3% 3.4% 4.2% 

Lime Kiln 8.9% 82.8% 3.4% 4.6% 

Recovery Boiler 27.3% 63.8% 2.7% 6.3% 

Power Boiler 3.6% 79.3% 6.3% 10.8%

Within 300 kilometers of the Mill two Class I Areas have been identified with visibility 

as an important air quality related value: 

1. St. Marks National Wilderness Area (112 km from Mill) 

2. Okefenokee National Wilderness Area (244 km from Mill) 

Figure 2 presents a simplified map in the UTM NAD27 projection with the arrangement 

of the Mill and the two Class I areas. 

700 750 800 850 900 950

UTM East (km)

Figure 2. Mandatory Class I Area Receptors within 300km of GP Cedar Springs

3350

3400

3450

U

T

M

N

orth (k

m)

CSO 

Okefenokee

St. Marks
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August 1, 2008 (Revised) 

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3.0 VISTAS CONTRIBUTION TO CALPUFF MODELING 

For this application of BART Modeling, VISTAS and EPD have made available the 

following data bases developed by the VISTAS Technical Contractor: 

• VISTAS version of the CALPUFF modeling system, maintained on the 

VISTAS Technical Contractor website. 

• 4-km CALMET output files for 2001, 2002, and 2003 produced as described 

in the VISTAS Common Protocol. 

• CALMET with a software modification to allow the meteorological data 

inputs into CALMET to be used to generate finer grid CALMET files without 

having to go back to the original MM5 output files 

• File with CALPUFF model configuration and settings sufficient to replicate 

CALPUFF modeling done for VISTAS using 12 km CALMET. 
Cedar Springs Mill BART Exemption Report 

August 1, 2008 (Revised) 

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4.0 MODEL DISCUSSION

4.1 General Procedures 

GP is beginning with the most refined dataset available from VISTAS. The fine grid 

analyses use the 98th percentile impact value for the 24-hr average at each Class I area. 

The analysis will use either the 8th highest day in each year or the 22nd highest day in the 

3-year period, whichever is more conservative. 

The VISTAS Common Modeling Protocol consistently recommends conservative 

assumptions. Individual States ultimately have responsibility to determine which, if any, 

BART controls are recommended in their State Implementation Plans (SIPs). The 

VISTAS protocol presents additional detailed information on the meteorological fields, 

and specific settings for CALPUFF and CALPOST (see section 4.33 of the VISTAS 

Common Modeling Protocol). 

4.2 CALPUFF Configuration 

Source emissions should be defined using the maximum 24-hour actual emission rate 

during normal operation for the most recent 3 or 5 years. If maximum 24-hr actual 

emissions are not available, continuous emissions data, permit allowable emissions, 

potential emissions, and emissions factors from AP-42 source profiles may be used as 

available. As described in Section 2 of this report, GP used allowable emissions to 

demonstrate that two alternative operating scenarios neither cause nor contribute to 

visibility impairment. 

GP completed the analysis with the Domain #4 4-km refined grid meteorological datasets 

provided by VISTAS. Figure 3 presents the modeling domain, the Class I Area model 

receptors and Mill. 
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800 900 1000 1100 1200 1300 1400 1500 1600 1700

LCC East (km)

Figure 3. CALPUFF Modeling Domain, Source and Receptors, GP Cedar Springs BART Analyses

-1200

-1100

-1000

-900

-800

-700

-600

-500

-400

-300

-200

LCC North (km)

Snow/Ice

Tundra

Barren

Wetland

Water

Forest

Range

Agriculture

Urban/Built-Up

Land Use

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

. .

. .

GP Mill

St. Marks

Okefenokee

The major features and options of the meteorological and dispersion model are 

summarized and discussed in the VISTAS Common Modeling Protocol. Specific 

configuration settings presented in the VISTAS Common Modeling Protocol are listed 

below: 

• Use default data provided by VISTAS for background concentrations of SO4 and 

total NO3 (HNO3 + NO3). GP utilized the more conservative default approach 

and also implemented the “ammonia limiting method” (ALM) with the 

POSTUTIL post-processor to re-partition the distribution of HNO3 and NO3

concentrations at each Class I area as a function of the temperature, relative 

humidity, and free ammonia during each hour. ALM re-partitioning using the 

default ammonia background level of 0.5 ppb was conducted in refined analyses. 
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• Use spatially- and temporally-variable hourly ozone data for observation stations 

within Domain 4 as prepared by VISTAS. A representative background value of 

50 ppb was entered into CALPUFF to substitute during hours for which no valid 

ozone concentrations were measured throughout the domain. 

• Use the Pasquill-Gifford dispersion method. 

• In CALPOST, use Method 6 with monthly average relative humidity for 

calculating extinction, as recommended by the EPA. Class I-area specific values 

of the relative humidity adjustment function were obtained from the U.S. EPA’s 

Guidance for Estimating Natural Visibility Conditions under the Regional Haze 

Rule (EPA-454/B-03-005), October 2003. 

• Use EPA default calculations of light extinction under average background 

conditions. The annual average natural background conditions were obtained 

from Appendix B of U.S. EPA’s Guidance for Estimating Natural Visibility 

Conditions under the Regional Haze Rule and were used to calculate the monthly 

equivalent fine particle (as soil) background concentration for each of Okefenokee 

and St. Marks as shown in the following equations. 

2 40.1 Mm 10 Mm 11 40. Mm for Okefenokee

10

61.7

10exp −1 −1 −1

 = = + = + ⇒ =











bback = bray bsoil bsoil bsoil

2 53.1 Mm 10 Mm 11 53. Mm for St.Marks

10

67.7

10 exp −1 −1 −1

 = = + = + ⇒ =











bback = bray bsoil bsoil bsoil

CALPOST calculates the 24-hour average visibility impairment as a function of the 

concentration of visibility-affecting pollutants using the default IMPROVE light 

extinction formula, which is summarized in the following equation. 

( ) ext background SO NO OC Soil Coarse ap Ray b Mm = b + b + b + b + b + b + b

−

4 3

1

,

, where 
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[( ) ] ( )

[ ] ( )

[ ]

[ ]

[ ]

[ ]

( )

( )

[ ] 3

1

3 4 3

4 4 2 4

Concentration in μg m

Relative Humidity Function

Rayleigh Scattering 10 Mm by default

10 EC

6.0 Coarse Mass

1Soil

4 OC

3 NH NO

3 NH SO

=

=

=

=

=

=

=

=

=

−

f RH

b

b

b

b

b

b f RH

b f RH

Ray

ap

Coarse

Soil

OC

NO

SO [( ) ]

[ ]

[ ]

[ ]

[ ]

[ ]

Rayleigh Scattering is scattering due to air molecules

EC denotes the concentration of elementalcarbon

Coarse Mass denotes the concentration of coarse dusts

Soil denotes the concentration of fine soils

OC denotes the concentration of organic carbon

NH NO denotes the ammoniumnitrate concentration

NH SO denotes the ammoniumsulfate concentration

4 3

4 2 4

As noted in the VISTAS BART Modeling Protocol, the U.S. EPA and the Regional 

Planning Organizations (including VISTAS) are evaluating whether refinements are 

warranted to the methods recommended in U.S. EPA’s guidance to calculate estimates of 

natural background visibility. For the purposes of calculating current, future, and natural 

background visibility at Class I areas as part of its reasonable progress analyses, VISTAS 

intends to present regional air quality modeling results using both the default and the 

newly revised IMPROVE light extinction formula. GP applied the revised IMPROVE 

formula to the analysis of visibility impairment at St. Marks to calculate a more refined 

result. 

In December 2005, the IMPROVE workgroup issued a report describing an alternative to 

the default formula used to estimate extinction from particle concentration measurements 

(referred to as the “2005 IMPROVE Report” hereafter). A final report was issued in 

March 2006 to present a thorough survey of estimates of mass scattering efficiencies 

from recent peer-reviewed literature and provisional recommendations for refinements to 

the IMPROVE equation (referred to as the “2006 IMPROVE Report” hereafter). 

Refinements in the revised IMPROVE formula include:

• Distinguishing the size (i.e., age) of secondary pollutants and growth factors for 

different sizes of particle species 

• Adding a site-specific Rayleigh scattering term to the formula to represent the 

dependence of Rayleigh scattering on air density (i.e., elevation) 
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• Adding a sea salt term, including a growth factor due to relative humidity 

• Adding a term for visibility impairment resulting from gaseous nitrogen dioxide 

(NO2) 

The revised IMPROVE light extinction algorithm takes the following form: 

bext ≈

( )[ ( ) ] ( )[ ( ) ]

( )[ ] ( )[ ]

[ ] [ ] [ ] [ ] [ ]

( )[ ] [ ] Site specific Rayleigh Scattering 2

Small Large

4 3 Small 4 3 Large

4 4 2 Small 4 4 2 Large

4.1 Sea Salt 33.0 NO

8.2 OC 1.6 OC 10 EC 1 PMF 6.0 PMC

4.2 NH NO 1.5 NH NO

2.2 NH SO 8.4 NH SO

+ +

+ + + + +

+ +

+ +

−

f RH b

f RH f RH

f RH f RH

SS

S L

S L

To facilitate the use of the revised IMPROVE algorithm for assessing BART 

applicability, the VISTAS Technical Contractor developed and distributed a spreadsheet 

tool to implement the revised IMPROVE light extinction algorithm, designated as the 

CALPOST-IMPROVE Processor Version 2 (September 29, 2006). This processor 

calculates the reconstructed light extinction using the revised IMPROVE algorithm and 

output from the current version of the CALPOST postprocessor. To implement the 

CALPOST-IMPROVE tool, three additional data points are required: background 

concentration of gaseous NO2, Rayleigh scattering parameter corrected for site-specific 

elevation, and an estimate of the average background sea salt aerosol concentration. 

Although other anthropogenic (stationary and mobile) sources contribute to background 

levels of NO2 at Class I areas, for the purposes of this analysis, the background NO2

concentration was assumed to be attributable only to BART-eligible sources at the CSO. 

The 24-hour average NO2 concentration for each day and receptor was calculated by 

separate CALPOST processing analyses, and converted from units of μg/m3 (default 

model output) to parts per billion as required by the tool. The NO2 concentration entered 

into the CALPOST-IMPROVE tool for each 24-hour average visibility impacts 

corresponded to the day and receptor at which the visibility impact occurs. CALPOST 

analyses for NO2 are included on the electronic media provided with this updated report. 

The NO2/NOX ratio was conservatively entered as 1.0 in the CALPOST-IMPROVE tool. 
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The 2005 IMPROVE Report describes the justification for using a site-specific Rayleigh 

scattering parameter in the revised light extinction algorithm. Rayleigh scattering refers 

to the scattering of light from the molecules of the air and is therefore dependent on the 

air density, which varies with temperature and pressure. Site-specific Rayleigh scattering 

was calculated using the standard atmospheric pressure corresponding to the monitoring 

site elevation and an estimated annual mean temperature. The temperature data were 

obtained from the nearest weather stations for time periods encompassing ten to thirty 

years and were interpolated to the monitoring site location. The 2005 IMPROVE Report 

tabulated site-specific values of Rayleigh scattering for locations at which IMPROVE 

monitors visibility, including St. Marks for which a value of 11 Mm-1 was calculated. 

Compared to the default Rayleigh scattering value of 10 Mm-1, the corrected values 

reflect the near-sea level elevation of Class I area evaluated in this analysis. 

The 2005 IMPROVE Report identified sea salt aerosols as an important component of 

natural visibility conditions, particularly in humid coastal environments such as the 

Class I areas potentially affected by GP’s CSO. The 2006 IMPROVE Report identifies 

sea salt as a statistically significant component of fine particle mass at St. Marks. 

Representative natural background sea salt concentrations were estimated for 

implementation in the CALPOST-IMPROVE processor for BART applicability analyses, 

including a concentration of 0.03 μg/m3

 for St. Marks. 
Cedar Springs Mill BART Exemption Report 

August 1, 2008 (Revised) 

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5.0 RESULTS AND DETERMINATION OF IMPAIRMENT 

5.1 Impact Threshold 

The final BART guidance recommends a threshold value of 0.5 dv change from natural 

conditions to define whether a source “contributes” to visibility impairment. The 

98th percentile, 24-hour average predicted impact at the Class I area, as calculated using 

CALPOST Method 6 (monthly average relative humidity values), is to be compared to 

this contribution threshold value. For this comparison, the predicted impact at the Class I 

area on any day is taken to be the highest 24-hr average impact at any receptor in the 

Class I area on that day. Because three meteorological data years (i.e., 2001 through 

2003) were evaluated, VISTAS recommends that the 98th percentile value be determined 

as the highest, 8th-high 24-hour average visibility impairment among three years or the 

22nd-highest 24-hour average visibility impairment over three years, whichever result is 

more conservative.

5.2 Presentation of Modeling Results 

Tables 7 and 8 summarize the CALPOST results for the 98th percentile, 24-hour average 

visibility impairment at Okefenokee and St. Marks, respectively. Each summary table 

presents the results from the two operating scenarios evaluated as well as the default and 

non-default processing methods described in this report. The default processing method 

does not utilize the ALM and utilizes CALPOST for the default IMPROVE light 

extinction calculation. Results for both Class I areas are also presented using the ALM 

with the default IMPROVE light extinction calculation. GP applied the refined 

IMPROVE equation to calculate refined impacts at St. Marks using the CALPOST 

results from the ALM analysis. 
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August 1, 2008 (Revised) 

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Table 7. Summary of CALPUFF Results, Okefenokee NWR 

98th Percentile, 24-hour Average 

Change in Visibility (∆dv)

Model Run 

2001-

2003 2001 2002 2003 

Operating Scenario 1 

Default Processing Without ALM 0.309 0.305 0.288 

Processing With ALM 0.30 0.306 0.300 0.281 

 

Operating Scenario 2 

Default Processing Without ALM 0.270 0.272 0.248 

Processing With ALM 0.266 0.267 0.266 0.241 

 

Table 8. Summary of CALPUFF Results, St. Marks NWR 

98th Percentile, 24-hour Average 

Change in Visibility (∆dv)

Model Run 

2001-

2003 2001 2002 2003 

Operating Scenario 1 

Default Processing Without ALM 0.495 0.622 0.469 

Processing With ALM 0.493 0.487 0.616 0.455 

Processing With ALM and Revised IMPROVE 0.408 0.403 0.499 0.368 

 

Operating Scenario 2 

Default Processing Without ALM 0.452 0.556 0.422 

Processing With ALM 0.463 0.451 0.550 0.404 

Processing With ALM and Revised IMPROVE 0.387 0.352 0.446 0.340 

 

The results presented in Tables 7 and 8 confirm GP’s determination that the Mill is 

exempt from BART because emissions from the BART-eligible source neither cause nor 

contribute to visibility impairment at any Class I area when operating in either of the two 

analyzed operating scenarios. 
Cedar Springs Mill BART Exemption Report 

August 1, 2008 (Revised) 

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APPENDIX 

Electronic Media File Index 

Electronic media enclosed with this report contain the input and output files from all 

CALPUFF, POSTUTIL, and CALPOST processing analyses. Each analysis is contained 

within its own appropriately named compressed file, which includes model executable 

files and batch files to manage the runstream. A consistent file naming convention is 

used throughout with the following general structure. Note that refined meteorological 

data files are not provided due to file size. Note also that path names in input files will 

need to be modified to represent the user’s directory structure when replicating these 

analyses. 

The following processing sequence was used for each meteorological data year: 

• CALPUFF was run separately for each source type (i.e., Power Boilers Nos. 1 

and 2, Recovery Boiler No. 3, Lime Kilns Nos. 1 and 2, and Smelt Dissolving 

Tank No. 3) because each source has a distinct PM10 speciation profile. 

• The total PM10 emission rate was modeled in CALPUFF and was subsequently 

speciated using the POSTUTIL post-processor. 

• CALSUM was then used to combine the concentrations of all pollutants 

(including speciated PM10 components) into a single concentration file. 

• POSTUTIL was run a second time to apply the “ammonia limiting method” 

(ALM), which calculates the HNO3/NO3 re-partitioning. The ALM analyses are 

run in three, 4-month blocks (A, B, C) due to an inherent limitation in the number 

of meteorological periods that can be processed when the ALM calculations are 

enabled in POSTUTIL. 

• Therefore, the APPEND utility must be run to concatenate the output files 

comprising these three blocks of data. 

• CALPOST was subsequently run three times for each Class I area 

1. Utilizing the “default” concentration output file without ALM processing 

2. Utilizing the concentration output file from ALM processing 

3. Computing daily average NO2 concentrations for use in the revised 

CALPOST-IMPROVE post-processing tool. 
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CALPUFF Runstream Files 

uuPUFFyy.fff 

uu = PB (Power Boilers Nos. 1 and 2), RB (Recovery Boiler No. 3), LK (Lime 

Kilns Nos. 1 and 2), SDT (Smelt Dissolving Tank No. 3) 

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively 

fff = inp denotes input files 

fff = lst denotes CALPUFF output summary files 

fff = con denotes CALPUFF output concentration files 

Domain 4 Ozone Data Files 

4OZyyyy.dat 

yyyy = 2001, 2002, and 2003 denotes respective data analysis years 

PM Speciation POSTUTIL Processing Files 

uuUTILyy.fff

uu = PB (Power Boilers Nos. 1 and 2), RB (Recovery Boiler No. 3), LK (Lime 

Kilns Nos. 1 and 2), SDT (Smelt Dissolving Tank No. 3) 

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively 

fff = inp denotes input files 

fff = lst denotes POSTUTIL output summary files 

fff = con denotes POSTUTIL output concentration files 

CALSUM Processing Files 

CALSUMyy.inp denotes CALSUM processing input file 

ALLSRCyy.con denotes output concentration files 

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively 
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August 1, 2008 (Revised) 

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Ammonia Limiting Method POSTUTIL Processing Files 

Note that in refined analyses for which the ammonia limiting method (ALM) was run, 

POSTUTIL is run in two separate steps, the first of which applies PM speciation for 

analysis in CALPOST, the second of which calculates the HNO3/NO3 re-partitioning. 

The ALM analyses are run in three, 4-month blocks (A, B, C) due to an inherent 

limitation in the number of meteorological periods that can be processed when the ALM 

calculations are enabled in POSTUTIL. Therefore, the APPEND utility must be run to 

concatenate the output files comprising these three blocks of data. CALPOST is 

subsequently run using this appended file. 

ALMUTIL_yyb.fff

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively 

b = A, B, and C denoting 4-month blocks January-April, May-August, SeptemberDecember, respectively 

fff = inp denotes input files 

fff = lst denotes POSTUTIL output summary files 

fff = con denotes POSTUTIL output concentration files 

ALMAPPENDyy.fff

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively 

fff = inp denotes input files 

fff = lst denotes APPEND output summary files 

CONCENyy.con = Appended POSTUTIL-ALM concentration file for year yy. 

CALPOST Runstream Files 

POST_aa_pp_yy.fff

yy = 01, 02, and 03 denotes data analysis years 2001, 2002, and 2003, respectively 

fff = inp denotes CALPOST input files 

fff = lst denotes CALPOST output summary files 

aa denotes the Class I areas considered in the analyses: 

STMK = St. Marks NWR 

OKEF = Okefenokee NWR 

pp denotes the processing method considered in the analyses: 

NOALM = processing using concentration files from CALSUM step without ALM 

VIS = processing using concentration files from POSUTIL-ALM step with ALM 

NO2 = processing for daily average NO2 concentrations for CALPOST-IMPROVE 
Cedar Springs Mill BART Exemption Report 

August 1, 2008 (Revised) 

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CALPOST-IMPROVE Microsoft Excel Spreadsheet Analyses

CALPOST-NewIMPROVE_St_Marks_yyyy.xls 

This spreadsheet comprises the VISTAS Revised CALPOST-IMPROVE spreadsheet tool 

calculations using CALPOST outputs for visibility impacts and calculated NO2

concentrations at St. Marks, where yyyy = 2001, 2002, and 2003, for data years 2001, 

2001, and 2003, respectively.